Impact of Bentonite Mining on Selecting Arthropods

Abstract

Arthropods were sampled in pitfall traps for 2 yr on bentonite mine spoils and adjacent, unmined big sagebrush (Artemisia tridentata) grasslands in southeastern Montana to assess the impacts of bentonite mining on selected arthropods, evaluate the success of early reclamation efforts in restoring arthropods to mined sites, and to identify limiting factors for colonization of spoils by arthropods. The most significant impacts on selected arthropods were on old, unreclaimed bentonite mine spoils, where after nearly 30 yr, numbers of 7 arthropod groups remained lower than on unmined sagebrush grasslands. Spoils covered with topsoil had higher captures of ground beetles (Carabidae) and crickets (Gryllidae) than unreclaimed spoils. And spoils covered with topsoil and seeded supported captures of most arachnids, Coleoptera, Hemiptera, and Formicidae similar to those on unmined sagebrush grasslands. Vegetative parameters measured in this study accounted for a portion of the variability in arthropod captures; however, microarthropod populations, arthropod vagility, and soil water contents may influence repopulation of mine spoils by some arthropods.